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Overview of Tape Research at CMRR

Jason WangCenter for Magnetic Recording Research

University of California, San Diego La Jolla CA 92093-0401

Phone:+1-858-534-7578, Fax:+1-858-534-2720E-mail: jason@talkelab.ucsd.edu

Presented at the THIC Meeting at the Hilton San Diego/Del MarDel Mar CA 92014-1901

on January 22, 2002

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STUDY OF TAPE EDGE WEAR

Graduate Student: Jason Wang

Advisor: Prof. Frank Talke

Center for Magnetic Recording Research, UCSD

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Outline

• Background• Experimental Setup and Procedures• Previous Results• Results since Last Meeting

Edge wear vs. tape speedEdge wear vs. different guide pad materialsEdge wear vs. different substrate materials

• Summary• Future Work

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Background• To increase storage density in tapes, track density

must be increased

• Increasing track density requires better tape guiding

• Tape guiding is done by using pressure pads

• Pressure pads cause wear which degrades performance

• SEM investigation observed tape edge wear

• AFM obtained a quantitative measurement to study tape edge wear as a function of guide force

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Experimental Setup and Procedures

• Measurement Method

• Creation of Indentation

• Guide Force Calibration

• Test Drive Setup

• AFM Measurement

• Data Processing

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Measurement Method* WEAR (∆d) = INITIAL DEPTH - REMAINING DEPTH

10 um

1 um, INITIAL

REFERENCE PLANE

REMAINING DEPTH

TAPEEDGE

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Measurement Method* WEAR (∆d) = INITIAL DEPTH - REMAINING DEPTH

SLIDER/GUIDE PAD

TAPEEDGE

REFERENCE PLANE

REMAINING DEPTH

1.6 mm

10 um

1 um, INITIAL

10 um

1 um, INITIAL

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Creation of Indentations

Reference Surface

Knife

Picture fromMicroscopeSliding Table

Dial Indicator

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Indentations under Microscope

AfterIndentation After Re-pack

A

B

2k Passes

B

A

4k Passes

B

A

Tape with 45-mN Guide Force

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Test Drive Setup

Removed Original Guide PadsBottom View

Slider

Tape

Suspension

Rollers withoutFlange

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AFM Measurement

Camera

ScanningTip

Reel ofTape

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View from AFM Monitor

Indentation

Scanning Tip

Cantilever Bar

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Data Processing

3-D image of edge wear at 30-mN guide force

Initial 6,000 Passes

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Section view of edge wear at 30-mN guide force

2,000 passes,

d=616 nm,delta d=65 nm

Initial,

d=681 nm,delta d=0 nm

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Previous Results

60-mN60-mN

45-mN

30-mN

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4k-pass

2k-pass

6k-pass

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Specific Wear Rate (WS) Calculation

NPdWS×∆

=

WS= Specific Wear Rate

∆d = Removed Depth (Wear)

P = Guide Force

N = Number of Passes

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60-mN60-mN45-mN

30-mN

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Results Since Last Meeting

• Wear vs. tape speed

• Wear vs. different guide pad materials

• Wear vs. different substrate materials (preliminary)

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2.5 m/s

1 m/s

4 m/s

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4k-pass

2k-pass

6k-pass

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2.5 m/s

1 m/s

4 m/s

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Particles inside indentation at 1 m/s (Sample-E)

Initial

2K

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Particles inside indentation at 1 m/s (Sample-G)

Initial 4K

2K 6K

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Particles inside indentation at 1 m/s (Sample-G)

Initial 4K

2K 6K

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• Wear vs. different guide pad materials

TAPE EDGE

REFERENCE INDENTATION10 um

SLIDER1.6 mm

CERAMIC or COPPER

PAD

4.85 mm

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Original Slider Pad

Ceramic Pad

Copper Alloy Pad

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Copper Pad Surface Roughness: Ra = 13.62

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Ceramic Pad Surface Roughness: Ra = 13.33

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Test Drive Setup for Ceramic and Copper Pad

Ceramic Pad Copper Pad

Rollers withoutFlange

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Copper

Ceramic

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Copper

Ceramic

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Tape elongation was observed

6k-pass4k-pass

2k-passInitial

Indentations under Microscope(Sample-H w/ ceramic pad)

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Initial 2k-pass

4k-pass 6k-pass

Indentations under Microscope(Sample-I w/ copper pad)

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Wear Mark on Copper Pad after 6,000 Passes

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Wear mark measured by WYKO

3 um

40 um

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• Wear vs. different substrate materials(preliminary)

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Data Sheet for Tape Samples

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Difficulties in this study• Packing (staggering) problem was found by using DLT tape on LTO drive• Tape edge’s surface variation is too large to measure from AFM

Aramid tape under microscope

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Summary• Tape edge wear as a function of tape speed and different guide pad materials was evaluated.

• Tape edge wear increases with increasing tape speed.

• Regarding to the effect of guide pad materials on tape edge wear, the ceramic pad caused more edge wear than the copper pad.

• Edge wear was negligible between 2,000 to 6,000 passes when the copper pad was used.

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Summary• Tape elongation was observed between 2,000 to 6,000 passes

• The specific wear rate decreases with increasing number of passes. This happened in all three experiments (wear vs. guide force, tape speed and guide pad materials).

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Future Work• Continue tape edge wear with respect to different substrate materials (PET, PEN and Aramid)

• Study edge wear as a function of tape tension and guide surface roughness

• Determine the effect of thermal conductivity and hardness on tape edge wear

• Evaluate the tape edge wear as a function of tape path misalignment